Here's some yarn to spin:

If responding to a recommendation demanded by someone other than the thread-owner, is it advertisement?
If not, what happens if a malicious user creates users posing questions as a method of advertisement?

Now, assume that the malicious user is the thread-creator - acting on behalf of a service for the purpose of Q&Advertisement.
Can the thread creator ask about a specific service/platform?

What happens if an honest platform is given a malicious Q&Advertisement campaign as an associative attack?

... and so on.